Field
The disclosure relates to a method, apparatus and system to facilitate surface cooling of a microchip (interchangeably, chip) within a three-dimensional (3D) stack of microchips using optical interconnect. Specifically, the disclosure relates to method, system and apparatus to provide optical interconnect for a microchip within a 3D stack so as to enable inter-layer cooking of the microchip stack.
Description of Related Art
In conventional semiconductor fabrication processes, semiconductor microchips are frequently attached to other chips or other electronic structures. The attachment of a semiconductor chip is frequently accomplished by one of two techniques. The first technique is a wire bonding process in which each of a series of I/O bump terminals on a chip built on an aluminum bonding pad is sequentially bonded to the connecting pads on a substrate. The second technique is a flip chip attachment method in which all the I/O bumps on a semiconductor chip are first terminated with a solder material. A frequently used solder material is a lead/tin composition with high melting temperature alloy. The semiconductor chip is then flipped over and the solder bumps are aligned and reflowed in a reflow furnace to effect all the I/O connections with the bonding pads on the substrate. One advantage achieved by the flip chip process is its applicability to very high density CMOS circuits and its high reliability in the interconnects formed when compared to the wire bonding process.
Within a stack of tightly connected chips, there is no direct physical access to planar layers. Thus, cooling is primarily done by removing heat from the edges of the chip stack. Additional means for removing heat includes adding heat sinks to one or more sides of the chips. However, heat sinks also contact only one side of the chip. Heatsinks, even when coupled with heat removing fins, fail to rapidly remove heat from the center of the chip stack. Moreover, heat sinks adversely increase spatial requirement of the chip stack. There is a need for a method and apparatus to provide rapid cooling to a chip stack that overcomes these and other deficiencies of the art.